bootcamp not burning support software to disk

Hi,

Basically I'm trying to install windows 7 ultimate on to my mac running lion 10.7.5 I tried to burn the iso file to disk through disk utility twice and when prompted by bootcamp assistant to insert the iso disk for installation I get a message saying I inserted a blank disk. After this I exited bootcamp and put in the disk that is suppose to contain the support software and its showing up blank aswell, the disks are 4.7gb so theres enough space I'm trying to burn the iso file with simply burns now to see if that will work for that but i have no idea how to get the support software on to disk as i can't find it online to download anywhere and i dont have a usb drive big enough please help if you can thank you.